Yet I couldn't get past some of the problems found in accepting the common position. If Jesus "paid for" our sins and that means we have no sin-debt, then what is justification, what is faith? What is the point of those? We would have been free 2,000 years ago, technically.
I will not deal with the extent of the atonement in this post, but I will deal with the difference in the nature of the atonement and why it is important. The thing that is tough is using technical terms -I had more than a few people look at me like I'm crazy or looking in too much detail by using such technical words. The assumption is that fancy language represents minute details which are of little consequence. For me, seeing the difference between a penal and pecuniary satisfaction made a world of difference.
Let me first say that the Bible does use language that relates to both ideas -penal, with His satisfaction pertaining to moral crimes and law; and pecuniary or commercial, with His satisfaction being like a payment of debt. In my studies, I have come to believe that while His satisfaction may be like (metaphorically) a payment of debt in some ways, it is properly a moral or penal satisfaction, not a literal debt payment. Below I will try to explain the difference.
Commercial or pecuniary satisfaction: With a pecuniary matter, the claim is on something owed. It is a debt, and there is a debtor and a Creditor. The "satisfaction" is a literal payment of the debt. It really doesn't matter who pays the debt, so long as the amount is paid, and then the debtor is legally freed ipso facto once payment is made. In fact, the Creditor cannot legally add any conditions or qualifications or anything. If the debt was paid for you, you are freed from all obligation, and you, legally, have to be. The Creditor (God) can't legally refuse it. I believe most argumentation that posits things like the "double-jeopardy" argument is coming from commercial assumptions about the death of Christ.
Here is an example: We go out to lunch together and decide to pay each our own way. You are feeling hungry, so you rack up a bill of $50. You don't have that. Being a gracious and generous person, I go up to the cashier and pay your bill. Now, the manager cannot come up to you and say, "Wait... You have to do this for me to take his payment for you." If I pay your bill with my money, it makes no difference to the cashier. Your debt is gone. In fact, maybe you decided the food was terrible and left early. You don't even know that I paid for you. You don't have to be thankful, you don't have to "sign here," you don't have to accept it. I paid your debt, and the obligation is immediately dissolved by the very act of my payment. The "creditor" no longer has any just claim because the thing owed has been paid.
One obvious problem should come up... how do you avoid making faith and conversion and justification meaningless? If your debt was paid and you were freed, legally, by that payment itself, then does that mean you were justified even before you were born? Were you justified before you believed? Were you justified in eternity past (historical heresy alert)? Is faith just a name-tag that says, "I'm elect?" Or is it a true instrument which joins us to the merits of Christ? I hope you can see that there is no place for being "joined" to any merits if we are assuming the commercial schema. Jesus paid the debt, and it was paid -you are free. That's it. I don't believe this is what the Bible says at all, yet many Calvinists assume these categories without even knowing it and without seeing how taking them consistently really challenges the doctrine of justification through faith alone.
Penal satisfaction: With this type of satisfaction, the legal claim is on the person and not on a thing or amount owed. You are a traitor, and you are sentenced to death. The Lawgiver is not bound to even consider pardoning you -to even consider it is gracious. Yet, the Lawgiver makes an arrangement with a Substitute who will suffer that which is morally suitable to your sentence. The way or conditions upon which the merits of the Substitute accrue to you, the guilty person, are purely at the discretion of the Lawgiver and His arragement. He can construe of any conditions He wishes for legally crediting the Substitute's satisfaction to you and thus pardoning you. What "condition" does He set forth? That you pay for it? That you try really hard? That you self-flagellate? No... that you humbly turn to Him and accept of this Substitute by faith. This "legal crediting" through the instrumental "condition" (don't be confused and assume that a condition implies merit) is what we call "justification." And, as Paul wrote in Romans 4:16, it is by faith so that it may accord with grace. The application of the merits of the legal Substitute is through faith... so that it may accord with grace, a gift received rather than something earned.
I hope you can see a few things about this right away. First, it does justice to the fact that Jesus actually accomplished something on the cross. His satisfaction was a full satisfaction to God's justice and applicable and equitable to our fallen human curse due both to Christ's infinite worth and to God's gracious arrangement to take the sufferings of His Son as a legal Substitute. Second, it does justice to the clear Biblical distinction between Christ's satisfaction and the application of it to a sinner (justification). It doesn't confuse or confound the offering of Christ with its application. Third, it means that the double-jeopardy argument doesn't really fit. Under the penal model, the Substitute can suffer as a substitute, and it may, at least hypothetically, never benefit anybody. It would be an injustice and fall under "double-jeopardy" only if the Lawgiver justified a sinner and then condemned him later for the same crimes. I hope you can see this is different from the usual line of reasoning.
In case what I have explained is still not making sense, here are the words of Charles Hodge on the subject:
"Now there are two kinds of satisfaction, which, as they differ essentially in their nature and effects, should not be confounded. The one is pecuniary or commercial, the other is penal or forensic. When a debtor pays the demand of his creditor in full, he satisfies the claims and is entirely free from any further demands. In this case the thing paid is the precise sum due, neither more nor less. It is a simple matter of an exact exchange, so much for so much. There can be no condescension, mercy, or grace on the part of a creditor receiving the payment of a debt. It matters not to him by whom the debt is paid, whether by the debtor himbself or by some one in his stead, for the claim of the creditor is simply upon the amount due and not upon the person of the debtor. In the case of crimes [penal] the matter is different. The demand is then uopn the offender. He himself is liable. In human courts substitution is out of the question. The essential point in matters of crime is not the nature of the penalty, but who shall suffer. The soul that sins, it shall die... Provision of a substitute to bear the penalty in the place of the criminial would be to the offender of a matter of pure grace enhanced in proportion to the dignity of the substitute and the greatness of the evil from which the criminal is delivered. Moreover, in the case of crimes [penal, still] the penalty need not be (and very rarely is) of the nature of the injury inflicted. All that is required is that it should be a just equivalent... Another important difference between pecuniary and penal satisfaction is that in the former case the very act serves to liberate; that is, the moment the debt is paid, the debtor is completely free. There is no dely, nor are any conditions attached to his deliverance. But in the case of a criminal, as he has no claim to have a substitute take his place, if one be provided, the terms on which the benefits of his substitution shall accrue to the offender are matters of agreement or covenant between the subsitute and the magistrate who represents justice. The deliverance of the offender may be immediate, unconditional, and complete; or it may be deferred, suspended on certaion conditions, and only gradually bestowed." (Systematic Theology.. abridged edition, Soteriology, definition of terms, satisfaction)
Hodge goes on to continue discussing the penal view, which he believes is the Biblical view (and I agree :) ). To me, understanding that there are other categories and another way of thinking about the nature of the atonement, one which fits the Biblical data and clears up a lot of confusion, has been paramount in my theological shift away from the more common conception of limited atonement (Owen-style) to the arguably more historical Reformed position.... which is that Jesus died for all, but especially for the elect.